| Co-Investigator(Kenkyū-buntansha) |
HARIMA Takahiro Hiroshima University, Medical and Dental Hospital, Research Associate, 医学部・歯学部附属病院, 助手 (90343293)
FUJITANI Morioki Hiroshima University, Graduate School of Biomedical Sciences, Associate Professor, 大学院・医歯薬学総合研究科, 助教授 (60190055)
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| Research Abstract |
In order to evaluate whether laser ablation affect the dentin bonding, 1) adhesive properties of two resin bonding systems to Er : YAG or CO2 laser-irradiated dentin, 2) surface characteristics of laced dentin, and 3) effects of configuration factor of cavities (C-factor) on bond strengths of adhesives, were investigated. The ultimate objective was to establish the guideline to laser application for dentin caries treatment
Wedge-shaped defects (WSD) and #600-finished flat dentin surfaces were prepared in the freshly extracted bovine teeth and were irradiated by Er : YAG (Erwin^R, 60mJ, 10pps) or CO2 (Topal^R, 1W, 0.3 sec) laser. They were placed with Clearfil Mega Bond/AP-X or Single Bond/Z100, and were stored in distilled water at 37℃ for 24 hours. The bond strengths were examined with the micro tensile bond test, whereas the surface characteristics of laced dentin were analyzed using light microscope, scanning electron microscope, transmission electron microscope and infrared thermography. Furthermore, the staining properties of the caries detecting solution were examined on the laced dentin surface
Laser ablation of dentin reduced adhesive properties of resin bonding systems. The so-called "laser-etching" might not be effective in promoting the adhesion. Subsurface layer of laced dentin was mechanically weakened due to the formation of structural defects and heat denatured layer, leading to considerably lower adhesive properties of resin bonding systems. Lower bond strengths were obtained in the WSDs, as compared with the flat surfaces. The laser-irradiated sound dentin was stained by the caries detecting solution
It was concluded that Er : YAG or CO2 laser ablation of dentin affected the adhesive properties of resin bonding systems. At the present moment, many problems have to be investigated and resolved to establish the guideline to laser applications for dentin caries treatment
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